Imagine 112 miles. Beyond the distance you can walk. If you get in your car and get on a highway, it is almost two hours of travel time. Now compare that distance to three inches. about the length of the longest finger of an adult. Three inches out of 112 miles. In relative terms, that is the distance human beings have travelled into space as compared to the distance we must travel to reach the nearest star. In late 1968, human beings traveled to the moon, circled it and returned. Proxima Centauri is 4.24 light-years away. Three inches out of 112 miles.
There is no evidence at all that there is intelligent life on Proxima Centauri, but for the sake of this mental exercise, let's assume there is a race similar in technological advancement to what we have achieved. Proxima Centauri has exoplanets, with one of them circling in the so-called ' goldilocks zone'. But just keep in your mind, three inches out of 112 miles.
The world's first nuclear bomb was detonated on July 16, 1945. It would take 24 years and 4 days for us to first walk on the moon. At the time we finally made it to the moon, there were three countries with enough nuclear weapons to completely end life on earth, there were another two with enough nuclear weapons to send us back to the stone age via a nuclear winter.
So how does this all relate to an Angry Alien? Evolution. We became humans because we ' won ' evolution. We are able to survive anywhere on earth, we can kill any other species with ease. In fact, we can eradicate species without even trying. Evolution is like a file that sharpens us to survive and dominate and that is what has happened to humans. Our desire to protect 'us' and kill ' them' was forced on us by evolution and is in the very DNA we use to replicate.
The problem of course is that it was never just humans versus environment or humans versus other species. Evolution also favors tribalism, where my family and friends are more important to me than your family and friends. From the earliest days tribes fought against tribes in order to breed and evolve. We formed larger tribes, called them countries, and then went to war against other countries, because evolution demands that I want my people to breed and evolve, rather than your people. If you don't look like my tribe, if you don't have the same customs as my tribe, then evolution tells me that you are wrong. It is racism, but it also is in all of our DNA. If human beings all had the exact same skin color, we would kill ourselves over eye color or hair color. My tribe must survive.
We created religion, and then the tribal nature in our genes tells us that my religion is right and I must kill people in your religion. Christian tribes tried to kill Muslim tribes, and then when that was over, Christian Catholics tribes and Christian Protestant tribes took a turn trying to kill each other.
The price we paid for winning evolution is that tribalism is such a core part of our instincts that we can never overcome it. We are destroying our environment, and one of the biggest reasons why is that tribes (countries) do not want to throttle back their economy and lose an economic war against other tribes. At every point in our attempt to save our environment, we primarily are thwarted by tribalism.
My belief is that the very forces of evolution that allowed us to win, require us to be extreme tribalists. It is all 'us vs them' including everything from nuclear weapons all the way down to little league baseball. We are competitive to a fault because we never would have survived evolution without being it. From a destruction standpoint, we are capable of self-exterminating in countless ways, nuclear weapons, biological weapons, environmental destruction... we can already do all these things, and yet when it comes to exploration, we have traveled but three inches out of 112 miles necessary to visit the nearest exoplanet. There is no doubt in my mind, based on how evolution works, that any intelligent life form, by the very nature of winning evolution, will be in the same angry, tribalistic situation. The competitive tribalism will cause their self-extinctions long before they could travel to distant stars. Evolution demands it.